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Biomedical subjects

J Sakamoto

Publications and source records attributed to J Sakamoto.

At least 37 records · Page 2Linked to original sources
PubMed2000

SEREX analysis of gastric cancer antigens.

Stomach cancer is the major malignancy in Japan and one of the most common cancers worldwide. To establish the basis for an immunotherapeutic approach to stomach cancer, we have initiated an analysis of stomach cancer antigens recognized by human immunoglobulin G (IgG) antibodies using SE-REX, a powerful expression cloning method developed by Dr. M. Pfreundschuh's group. Five stomach cancer cDNA libraries have been screened with autologous patient sera: one moderately differentiated adenocarcinoma; two poorly differentiated adenocarcinomas; and two scirrhous-type poorly differentiated adenocarcinomas of Borrmann type 4, the most devastating form of stomach cancer. Based on the reactivities of clones with autologous IgG antibodies, an average of 50 independent clones from each library and a total of 297 clones were isolated. DNA sequencing revealed that these 297 clones were derived from 136 different genes. Comparison of the 136 genes to sequences in DNA databases showed that 95 are previously identified genes and 41 are newly identified in this study. The antigens are derived from various genes including a chimeric gene between E-cadherin and an unknown gene Y, AKT oncogene, genes overexpressed in stomach cancers, genes of which the transcripts are alternatively or aberrantly spliced, and genes known to be involved in autoimmune diseases. Thus stomach cancer patients can generate an immune response against a surprisingly diverse set of gene products. To identify antigens potentially useful in the diagnosis and therapy of gastric cancer, all 136 genes were tested for their reactivities with a panel of sera from 44 gastric cancer patients (17 women and 27 men, aged 35-81 years) and with a panel of sera from 100 control individuals with no previous history of cancer but some of whom had gastritis (55 women and 45 men, aged 30-69 years). Eleven antigens showed reactivity only with a certain proportion of cancer patient sera but not with any control sera. An additional 12 antigens elicited antibody production at a much higher frequency in cancer patients than in control individuals. To evaluate the clinical usefulness of these antigens we are now examining their expression in normal and malignant tissues.

Adult↗
PubMed2000

Idiopathic portal hypertension associated with systemic lupus erythematosus.

A case of idiopathic portal hypertension (IPH) associated with systemic lupus erythematosus (SLE) is reported in a 38-year-old man who had been diagnosed with SLE and treated for 18 years. Esophageal varices. found in 1994 on endoscopic examination, had been followed up for 2 years. On July 16, 1996, he was admitted to Nagoya University Hospital because there was a high risk of bleeding from the esophageal varices due to severe thrombocytopenia. As partial splenic embolization had temporarily controlled the thrombocytopenia, splenectomy and devascularization of the stomach vessels were performed after endoscopic ligation of the esophageal varices. Histological specimens of wedge biopsied liver showed chronic inactive hepatitis without cirrhosis. The presence of anticardiolipin antibody, indicated by positivity for lupus anticoagulant, was suggestive of the presence of a common immunological mechanism in the etiology of SLE and IPH.

Adult↗
PubMed2000

Active site structure of SoxB-type cytochrome bo3 oxidase from thermophilic Bacillus.

Two-subunit SoxB-type cytochrome c oxidase in Bacillus stearothermophilus was over-produced, purified, and examined for its active site structures by electron paramagnetic resonance (EPR) and resonance Raman (RR) spectroscopies. This is cytochrome bo3 oxidase containing heme B at the low-spin heme site and heme O at the high-spin heme site of the binuclear center. EPR spectra of the enzyme in the oxidized form indicated that structures of the high-spin heme O and the low-spin heme B were similar to those of SoxM-type oxidases based on the signals at g=6.1, and g=3.04. However, the EPR signals from the CuA center and the integer spin system at the binuclear center showed slight differences. RR spectra of the oxidized form showed that heme O was in a 6-coordinated high-spin (nu3 = 1472 cm(-1)), and heme B was in a 6-coordinated low-spin (nu3 = 1500 cm(-1)) state. The Fe2+-His stretching mode was observed at 211 cm(-1), indicating that the Fe2+-His bond strength is not so much different from those of SoxM-type oxidases. On the contrary, both the Fe2+-CO stretching and Fe2+-C-O bending modes differed distinctly from those of SoxM-type enzymes, suggesting some differences in the coordination geometry and the protein structure in the proximity of bound CO in cytochrome bo3 from those of SoxM-type enzymes.

Binding Sites↗
PubMed2000

Saturation transfer ratio imaging in invasive ductal carcinomas of the breast.

A prospective study was performed to investigate the correlations between saturation transfer ratio (STR) and histologic parameters of invasive ductal carcinomas in human breast. The histologic parameters investigated were the extent of fibrosis in the intercellular matrix, dysplastic changes of nuclei, and mitotic index. Twenty-seven patients with breast carcinoma were examined using an off-resonance saturation pulse in conjunction with conventional field-echo T(1)-weighted imaging at frequency offsets of 448 Hz and 1200 Hz from water resonance. The values of STR at frequency offset of 1200 Hz (STR(1200)) increased from non-scirrhous carcinoma to scirrhous carcinoma. Although STR(1200) showed correlation with the extent of fibrosis in the intercellular matrix (p<0.01, n = 27), they did not correlate with the dysplastic changes of nuclei or mitotic index. On the other hand, the values of STR at frequency offset of 448 Hz (STR(448)) demonstrated close correlation to dysplastic changes of nuclei and mitotic index (p<0.01, n = 27). STR(1200) correlates with the structural characteristics and STR(448) correlates with the nature of malignant cells with regard to nuclear dysplasia and mitotic potential.

Adenocarcinoma, Scirrhous↗
PubMed2000

Formation and structure of artificial cellulose spherulites via enzymatic polymerization.

The in-depth structural analysis of spherulites of artificial cellulose, formed by the enzymatic polymerization of cellobiosyl fluoride, is reported. Both positive- and negative-type spherulites were observed by polarization optical microscopy. Scanning electron microscopy revealed that the negative spherulites have a three-dimensional round shape, where platelike single crystals of the artificial cellulose originate radially from the center. Transmission electron microscopy confirmed that the cellulose chains orient vertically in the platelike crystals, explaining the observation of negative-type spherulites by polarization optical microscopy. Cellulose spherulites can be formed easily via the enzymatic polymerization process, and the occurrence of both positive- and negative-type spherulites is proposed, due to two independent polymerization mechanisms.

Carbohydrate Sequence↗
PubMed2000

Energy-yielding properties of SoxB-type cytochrome bo(3) terminal oxidase: analyses involving Bacillus stearothermophilus K1041 and its mutant strains.

We isolated a K17q8 mutant from K17 mutant cells of Bacillus stearothermophilus which contain SoxB-type cytochrome bo(3) as well as cytochrome bd but not SoxM-type cytochrome caa(3), which is the main terminal oxidase in B. stearothermophilus K1041. The respiration of K17q8 was highly sensitive to as little as 10 microM cyanide, indicating that the main terminal oxidase is cytochrome bo(3). The aerobic growth yield of K17q8 was lower than that of wild-type K1041, but higher than that of parental K17. The H(+)/O ratio of K17q8 was about 5, i.e. a little lower than the 6.1-6.5 of K1041, but higher than the 2.9-3.1 of K17 [Sone et al. (1999) J. Biosci. Bioeng. 87, 495-499]. Analyses of membrane fragments indicated that K17q8 contains about 0.2 nmol cytochrome bo(3) per mg membrane protein, and scarcely any subunits of cytochromes caa(3) and bd. From the membrane fraction of K17q8, cytochrome bo(3) was purified and shown to be composed of two subunits with apparent molecular masses of 56 and 19 kDa. The enzyme contained protoheme IX and heme O, as the main low-spin heme and high-spin heme. Analysis of the substrate specificity indicated that the high-affinity site is very specific to cytochrome c-551, a cytochrome c which is a membrane-bound lipoprotein of thermophilic Bacillus. The I(50) of purified cytochrome bo(3) was determined to be 4 microM, indicating that cytochrome bo(3) among the three terminal oxidases in B. stearothermophilus was most susceptible to cyanide. The respiration of K17q8 was mostly inhibited by the addition of cyanide at this concentration.

Bacterial Proteins↗
PubMed2000

The ratio of splicing variants of MGC-24/CD164, a sialomucin, correlates with the metastatic potential of colorectal carcinomas.

MGC-24/CD164 is a sialomucin expressed in many normal and cancerous tissues. In humans, soluble and transmembrane forms of MGC-24 are produced by alternative splicing. The total MGC-24 RNA level was found to be lower in human colorectal carcinomas as compared with the adjacent normal mucosal tissues. Lower MGC-24 mRNA levels in colon carcinomas and in the adjacent normal mucosa epithelium correlate with lymphatic vessel invasion by the carcinoma. The ratio of the soluble form to the transmembrane form of the mRNA in colorectal carcinomas was determined by ribonuclease protection assay. Higher ratios were correlated with less venous invasion and less remote metastasis, which became evident during postoperative observation.

Alternative Splicing↗
PubMed2000

Contribution of malonyl-CoA decarboxylase to the high fatty acid oxidation rates seen in the diabetic heart.

Myocardial glucose oxidation is markedly reduced in the uncontrolled diabetic. We determined whether this was due to direct biochemical changes in the heart or whether this was due to altered circulating levels of insulin and substrates that can be seen in the diabetic. Isolated working hearts from control or diabetic rats (streptozotocin, 55 mg/kg iv administered 6 wk before study) were aerobically perfused with either 5 mM [(14)C]glucose and 0.4 mM [(3)H]palmitate (low-fat/low-glucose buffer) or 20 mM [(14)C]glucose and 1.2 mM [(3)H]palmitate (high-fat/high-glucose buffer) +/-100 microU/ml insulin. The presence of insulin increased glucose oxidation in control hearts perfused with low-fat/low-glucose buffer from 553 +/- 85 to 1,150 +/- 147 nmol x g dry wt(-1) x min(-1) (P < 0. 05). If control hearts were perfused with high-fat/high-glucose buffer, palmitate oxidation was significantly increased by 112% (P < 0.05), but glucose oxidation decreased to 55% of values seen in the low-fat/low-glucose group (P < 0.05). In diabetic hearts, glucose oxidation was very low in hearts perfused with low-fat/low-glucose buffer (9 +/- 1 nmol x g dry wt(-1) x min(-1)) and was not altered by insulin or high-fat/high-glucose buffer. These results suggest that neither circulating levels of substrates nor insulin was responsible for the reduced glucose oxidation in diabetic hearts. To determine if subcellular changes in the control of fatty acid oxidation contribute to these changes, we measured the activity of three enzymes involved in the control of fatty acid oxidation; AMP-activated protein kinase (AMPK), acetyl-CoA carboxylase (ACC), and malonyl-CoA decarboxylase (MCD). Although AMPK and ACC activity in control and diabetic hearts was not different, MCD activity and expression in all diabetic rat heart perfusion groups were significantly higher than that seen in corresponding control hearts. These results suggest that an increased MCD activity contributes to the high fatty acid oxidation rates and reduced glucose oxidation rates seen in diabetic rat hearts.

AMP-Activated Protein Kinases↗
PubMed1999

Gene structure and quinol oxidase activity of a cytochrome bd-type oxidase from Bacillus stearothermophilus.

Gram-positive thermophilic Bacillus species contain cytochrome caa3-type cytochrome c oxidase as their main terminal oxidase in the respiratory chain. We previously identified and purified an alternative oxidase, cytochrome bd-type quinol oxidase, from a mutant of Bacillus stearothermophilus defective in the caa3-type oxidase activity (J. Sakamoto et al., FEMS Microbiol. Lett. 143 (1996) 151-158). Compared with proteobacterial counterparts, B. stearothermophilus cytochrome bd showed lower molecular weights of the two subunits, shorter wavelength of alpha-band absorption maximum due to heme D, and lower quinol oxidase activity. Preincubation with menaquinone-2 enhanced the enzyme activity up to 40 times, suggesting that, besides the catalytic site, there is another quinone-binding site which largely affects the enzyme activity. In order to clarify the molecular basis of the differences of cytochromes bd between B. stearothermophilus and proteobacteria, the genes encoding for the B. stearothermophilus bd was cloned based on its partial peptide sequences. The gene for subunit I (cbdA) encodes 448 amino acid residues with a molecular weight of 50195 Da, which is 14 and 17% shorter than those of Escherichia coli and Azotobacter vinelandii, respectively, and CbdA lacks the C-terminal half of the long hydrophilic loop between the putative transmembrane segments V and VI (Q loop), which has been suggested to include the substrate quinone-binding site for the E. coli enzyme. The gene for subunit II (cbdB) encodes 342 residues with a molecular weight of 38992 Da. Homology search indicated that the B. stearothermophilus cbdAB has the highest sequence similarity to ythAB in B. subtilis genome rather than to cydAB, the first set of cytochrome bd genes identified in the genome. Sequence comparison of cytochromes bd and their homologs from various organisms demonstrates that the proteins can be classified into two subfamilies, a proteobacterial type including E. coli bd and a more widely distributed type including the B. stearothermophilus enzyme, suggesting that the latter type is evolutionarily older.

Amino Acid Sequence↗
PubMed1999

Phase II trial of 5-fluorouracil and low-dose cisplatin in patients with squamous cell carcinoma of the esophagus.

A phase II study was conducted to determine the clinical efficacy and toxicity of 5-fluorouracil (5-FU) and low-dose cisplatin (CDDP) in patients with squamous cell carcinoma of the esophagus. Chemotherapy consisted of 5-FU at a dose of 330 mg/m2 per day, given as a 24-h infusion on days 1-7, and CDDP at a dose of 6 mg/m2 per day, given as a 2-h infusion on days 1-5. Either two or four cycles of chemotherapy were administered to 20 patients with stage III advanced esophageal carcinoma. All 20 patients were then assessed for response and toxicity. An objective response was demonstrated by 11 of the 20 patients, with one complete response (CR) and ten partial responses (PR), bringing the response rate to 55%, with a 95% confidence interval of 27% to 83%. Surgical resection of the tumor was performed in all 20 patients. One patient was found to have a grade 3 histological CR. The median survival of all the patients was 20.5 months, with a range of 4.5 to 48.0 months. Neutropenia and thrombocytopenia developed in five (25%) and two (10%) patients, respectively, and the nonhematologic toxicities were insignificant. The findings of this phase II study indicate that preoperative treatment using 5-FU and low-dose CDDP chemotherapy for patients with advanced esophageal carcinoma appears to achieve a high response rate after short-term administration without affecting the quality of sophisticated lymph node dissection.

Aged↗
PubMed1999

Treatment for empyema with bronchopleural fistulas using endobronchial occlusion coils: report of a case.

We report herein the case of a woman with bronchopleural fistulas treated with the endobronchial placement of vascular embolization coils. She was referred to our hospital to undergo lavage of a postoperative empyema. She had undergone an air plombage operation for pulmonary tuberculosis 9 years previously. However, bronchopleural fistulas occurred postoperatively and she had to continue the use of a chest drainage tube since then. Lavage of her empyema space with 5kE of OK-432 (Picibanil: Chugai) plus 100 mg minocycline was performed once every 2 weeks for 3 months, and the purulent discharge from the empyema remarkably decreased. Thereafter, the bronchopleural fistulas were occluded endobronchially by the placement of vascular embolization coils. Soon after the procedure, air leakage from the fistulas was stopped and the drainage tube was removed 2 days later. The patient remains well without any additional treatment at 20 months after this treatment. As treatment for empyema with bronchopleural fistulas, it would be worth trying to lavage the empyema space with OK-432 until it is cleaned out and to plug the fistulas by the endobronchial placement of embolization coils, before such radical operations as thoracoplasty and space-filling of the empyema are considered.

Bronchial Fistula↗
PubMed1999

Impact of splenectomy and immunochemotherapy on survival following gastrectomy for carcinoma: covariate interaction with immunosuppressive acidic protein, a serum marker for the host immune system. Tumor Marker Committee for the Study Group of Immunochemotherapy with PSK for Gastric Cancer.

The role of the spleen in tumor immunology is still controversial in that it can either enhance or suppress the antitumor immune response depending on the tumor-bearing host. To clarify this biphasic effect of the spleen, a clinical evaluation of splenectomy in conjunction with immunotherapy and the host immune status was performed in gastric cancer patients. The effect of splenectomy and immunotherapy in 253 gastric cancer patients enrolled in a prospective randomized trial (SIP) was analyzed using the Cox's proportional hazards model in terms of the covariate interaction of the preoperative immunosuppressive acidic protein (IAP) level. In patients with high IAP levels (>580 microg/ml) with predicted negative antitumor immune reactions, splenectomy improved the prognosis. In patients with lower IAP values, conversely, the preservation of the spleen and immunotherapy demonstrated a significant benefit to survival. The spleen was shown to have a biphasic activity in terms of its antitumor immune response depending on the IAP level of the patient. The effect of immunotherapy is significantly influenced by the activity of spleen cells. The preoperative IAP level is therefore considered to be a possible indicator for the effectiveness of splenectomy and immunotherapy in curatively resected gastric cancer patients.

Aged↗
PubMed1999

Developing bronchial fistulas as a late complication of extraperiosteal plombage.

A 65-year-old male, who underwent extraperiosteal plombage for pulmonary tuberculosis 46 years ago, was referred to our hospital due to relapsing hemosputa and pneumonia. A chest computed tomography scan revealed a bronchial fistula and a fluid collection in one Lucite ball. On May 20, 1996, a right-anterior thoracotomy was performed in a supine position. Five Lucite balls were removed, and the empyema space was tightly filled with an omental pedicle flap. Although the bronchial fistulas were not sutured directly, the air leakage from the drainage tube ceased 12 days later. Two years postoperatively the patient has remained well. Our simple approach of combining an anterior thoracotomy and replacement of an empyema space with an omental pedicle flap in the same posture, without closing bronchial fistulas, would be an easy procedure, and therefore exploitable in patients who have a similar problem.

Aged↗
PubMed1999

Reperfusion arrhythmias in the murine heart: their characteristics and alteration after ischemic preconditioning.

In this study, we examined the features of reperfusion arrhythmias and the effect of preconditioning (PC) in the mouse for future application of genetically engineered mice to study mechanisms of this type of arrhythmia. Under pentobarbital anesthesia, reperfusion arrhythmias were induced by temporary occlusion of the left anterior descending coronary artery and reperfusion in BALB/c AJc1 mice. In the first protocol, the coronary artery was occluded for periods ranging from 2 to 15 min and then reperfused. In the second protocol, hearts were preconditioned with 2- or 3-min ischemia and 5-min reperfusion prior to the 5 min of coronary occlusion. An electrocardiogram was recorded throughout the experiment, and arrhythmias were diagnosed according to the Lambeth Convention criteria. The incidences of reperfusion-induced ventricular tachycardia (VT) in hearts that received 2, 3, 5, 10 and 15-min ischemia (n = 10 approximately 14) were 0, 9, 73, 55 and 30 %, respectively. Ventricular fibrillation (VF) was not observed upon reperfusion regardless of the ischemia duration. PC with 2-min ischemia and with 3-min ischemia (n = 10 for each PC) reduced the incidences of reperfusion VT after 5-min ischemia to 40% and 10%, respectively. However, in mice that developed reperfusion VT, the VT duration was similar to that in non-preconditioned controls, ranging from 1 to 16 s. These results suggest that the relationship between ischemia duration and incidence of VT upon subsequent reperfusion is "bell shaped" and that PC has anti-arrhythmic effects in the mouse, as it does in anesthetized rat hearts. However, there appear to be differences in the incidence of reperfusion-induced VF and the duration of reperfusion VT between these species. Thus, the present murine preparation appears to be a useful model for studying the mechanism of reperfusion VT and PC, though it does not share all of the features of reperfusion arrhythmias with the anesthetized rat preparation.

Animals↗
PubMed1999

Direct correlationship between proton translocation and growth yield: an analysis of the respiratory chain of Bacillus stearothermophilus.

Thermophilic bacilli contain cytochrome caa3-type cytochrome c oxidase as the main terminal oxidase in the respiratory chain. A mutant strain, named K-17, lacking cytochrome caa3 and exhibiting very low N,N,N',N'-tetramethyl-p-phenylene diamine oxidase activity, was isolated by random mutation from Bacillus stearothermophilus K1041 (Sakamoto, J. et al., FEMS Microbiol. Lett., 143, 151-158, 1996). Comparing this mutant with the parent strain K1041, we observed the following differences in energy-yielding properties. (i) K-17 gave an cell yield less than one half of that of the wild type, although the doubling time of K-17 was only a little slower than that of the parent strain. (ii) In cellular respiration, the H+/O ratio of K-17 was 2.9-3.1, while that of the wild type was 6.1-6.5. (iii) A low concentration of cyanide inhibited endogenous respiration of the wild-type cells partly with a concomitant reduction of the H+/O ratio to around 3, while it did not significantly affect the respiration rate and the H+/O ratio of the K-17 cells. (iv) Cytochrome bd-type quinol oxidase seemed to operate in the wild-type cells when a low concentration (below 0.5 mM) of cyanide was added, while this enzyme is the main terminal oxidase in K-17. The K-17 cells also contained cytochrome b(o/a)3-type cytochrome c-551 oxidase. These results demonstrated that the combination of the enzymes involved in the respiratory chain determines the H+/O ratios of the cell and consequently the growth yield of the bacteria.

Journal Article↗
PubMed1999

Adjuvant therapy with oral fluoropyrimidines as main chemotherapeutic agents after curative resection for colorectal cancer: individual patient data meta-analysis of randomized trials.

BACKGROUND: Oral 5-fluorouracil and its prodrugs (tegafur, carmofur) is now being studied for adjuvant chemotherapy of curatively resected colorectal cancers. To evaluate the effect of these oral fluoropyrimidines (o-FPs), an individual patient data (IPD) meta-analysis of randomized clinical trials was performed in Japan as an inter-trialist group study. METHODS: Data from the three clinical trials in which postoperative adjuvant therapy with o-FPs was compared with surgery alone in patients with colorectal cancer were sought. IPD from a total of 4960 patients with follow-up periods of at least 5 years were analyzed. RESULTS: The results of the meta-analysis on an 'intention to treat' basis demonstrated a significant benefit of o-FPs in terms of the disease-free survival (DFS) of the total patients [risk ratio (RR) 0.830, 95% confidence interval (CI) 0.742-0.929, P = 0.001]. o-FPs were also demonstrated to be effective for survival in rectal cancer (RR 0.857, 95% CI 0.734-0.999, P = 0.049) and in Dukes'C colorectal cancer (RR 0.828, 95% CI 0.711-0.965, P = 0.016). CONCLUSION: The results suggest the advantage of long term o-FPs, possibly with the injection of mitomycin C, for prognosis for curatively resected colorectal cancer patients.

Administration, Oral↗
PubMed1999

Cloning of Bacillus stearothermophilus ctaA and heme A synthesis with the CtaA protein produced in Escherichia coli.

The Bacillus stearothermophilus ctaA gene, which is required for heme A synthesis, was found upstream of the ctaBCDEF/caaEABCD gene cluster as in B. subtilis and B. firmus. The deduced protein sequence indicate that CtaA is a 35-kDa intrinsic membrane protein with seven hydrophobic segments. Alignment of CtaA sequences showed conserved residues including histidines that may be involved in heme B binding and substrate binding. Expression of ctaA in E. coli resulted in increased formation of a membrane-bound b-type cytochrome, heme A production, and severe growth inhibition. Furthermore, B. stearothermophilus CtaA produced in E. coli was found to catalyze the conversion of heme O to heme A in vitro.

Amino Acid Sequence↗